Compounds (polymerizable compounds) having polymerizable groups are used as a raw material of various films. For example, a polymerizable composition containing a polymerizable compound is aligned in a liquid crystalline state and then polymerized, whereby a film-like polymer having a uniform alignment can be produced. A film produced in this manner can be used for a polarizing plate, a retardation film, and the like which are required in a display. In many cases, for satisfying the demanded optical characteristics, polymerization rate, solubility, melting point, glass transition temperature, film transparency, mechanical strength, surface hardness, heat resistance, and light resistance, a polymerizable composition containing two or more polymerizable compounds is used. In this case, the polymerizable compounds used are required to provide good physical properties to the polymerizable composition without any adverse effect on the other characteristics. In addition, by adding a chiral compound to such a polymerizable composition, aligning the polymerizable composition in a cholesteric liquid crystal state, and then polymerizing the composition, a film having a cholesteric structure can be produced. When production of a film having a cholesteric structure is intended, a polymerizable compound that can exist as a liquid crystal phase in a wide range of the temperature and has a high cholesteric alignment is required. When the polymerizable crystal liquid composition is used industrially, high storage stability is demanded so that the polymerizable compound in the components does not precipitate even when the composition is stored for a long period of time.
When a film having the cholesteric structure is used as an optical film in a display device or the like, it is required to have less alignment defects and to show small variation in selective reflection wavelength when placed in a high temperature state. However, when a polymerizable cholesteric liquid crystal composition is prepared to produce a film using a conventionally known material, there arise problems in that alignment defects are generated and the selective reflection wavelength greatly varies in storing the film at high temperature (PTL 1 and PTL 2). When such a film in which alignment defects are easily generated and the selective reflection wavelength is liable to vary is used, for example, in a display, there are problems in that the brightness of the screen becomes non-uniform, the color becomes unnatural, and intended optical characteristics become not achieved, after long term use, resulting in great deterioration in quality of a display product.
In addition, a retardation film which is used for optical compensation of a display and the like is intended to have less alignment defects and to show small variation in the phase difference when placed in a high temperature state. However, when a polymerizable liquid crystal composition is prepared to produce a film using a conventionally known material, there arise problems in that alignment defects are generated and the phase difference greatly varies in storing the film at high temperature (PTL 1 and PTL 2).